Oxygen therapy humidifier

May 31, 1955

2,709,577

H. L. POHNDORF ETAL

OXYGEN THERAPY HUMIDIFIER

Filed July 28, 1951

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ATTORNEY

2,709,577

Patented May 31, 1955

United States Patent Office

2,709,577

OXYGEN THERAPY HUMIDIFIER ^H ΟΛ1™ ^rf’ ^E- ^Ce™!°’ ^{George L}· Hammon, ^assi9>ors to National Welding Equipforniaⁱ °’’ ^Franc,sco> ^Callf-> a corporation of CaliApplication July 28, 1951, Serial No. 239,136

Claims. (CI. 261—2) his invention relates to an improved humidifier.

One important use of humidifiers is in connection with Of ™lT‘^!nleaV^{Or hos}P^itaI patients. Commercial tanks ot oxygen noimally maintain the gas under extremely high pressures and with no contained moisture. When the pressure of the gas is reduced, the gas remains at zero humidity and if administered that way to the patient, it will tend to dry out the lung tissues. Prolonged breathing of dry oxygen can be quite harmful; so it has become accepted practice to humidify the oxygen before the patient breathes it.

It is often desirable to saturate the oxygen, that is, to wet me gas to a humidity of approximately 100%. This makes it possible to produce gas of any desired humidity by mixing a known amount of the saturated gas (100% humidity) with a known amount of the dry gas (0% humidity) One trouble with humidifiers which have here ofore been used has been that they were not able to wet the dry gas to 100% humidity. Most of these prior art humidifiers have been mere bubblers—i. e. thev operated by bubbling the dry gas through a jar of water. Only the oxygen near the surface of the bubble came in contact with the water, and the balance of the oxygen inside the bubble remained relatively dry.

Another problem with bubblers has been that their efficiency decreased with increase in the pressure of the gas. The mgher the pressure of the gas introduced ^{the larger the} bubbles, and the larger the bubbles, the less gas that comes in contact with the water so the gas that goes out the outlet is less humid than desired.

Another fault with humidifiers of the bubbler type has been that the gas often carried over small droplets of water which were never evaporated. It is believed that such droplets, when carried into the lungs, sometimes induced pneumonia and aggravated the disease which the treatment was intended to cure.

Still another disadvantage of the humidifiers that have heretofore been in use is that they have required almost constant watching. The jars held a relatively small amount of water, and only a small proportion of this small amount was available for humidification. When the water level dropped, the bubbles traveled a shorter distance through the water, less gas came into contact with the water, and the humidity of the outgoing gas dropped. Aiso when the water level dropped only a short distance, it would fall below the gas inlet of the bubbler; so there was no humidification. This meant that the nurse had to watch the water level closely and had to add water frequently.

A more serious problem was the fact that many of such humidifiers were dangerous. The humidified oxygen has usually been conducted away from the jar by a flexible rubber hose, and this is usually the most desirable way to do it. However, when such a hose became kinked, or was stepped on, or otherwise collapsed, two dangers were present: First, the patient would not get enough oxygen to breathe so that he might suffocate. Second, the piessure of the gas would build up inside the jar, so that it was not uncommon for the jar to explode and scatter broken glass.

All these problems, and several others which will become apparent from this description, have been solved by the present invention. It provides a humidifier which will produce substantially 100% humid oxygen, free from droplets of water. It can be used with jars of relatively large volume and makes use of substantially all the water I in the jar; so the humidifier does not require frequent attention. Moreover, its efficiency will not drop as the water level drops, and the humidity will remain substantially constant so long as there is any water in the jar. Further, a unique warning system is. provided that sends out an audible signal when the gas pressure in the jar reaches a predetermined amount so that the nurse is called automatically and the patient is given more oxygen to breathe. At the same time, a relief valve permits escape.of excess gas and thereby prevents explosions from occurring.

Pj® structure which has solved these problems, and which has many other advantages that will be taken up m connection with the illustrative description includes a sealed jar haying an outlet and an inlet with a fixed orii!^e' ^or,'^^ce °P^ens into, or near to, a venturi chamber. The passage of oxygen through the venturi sucks water into the chamber through a long, flexible tube which may extend as long as necessary, up to the atmospheric limit for sucking water. Inside the venturi chamber the water is apparently broken up into millions of tiny droplets which are then introduced into the oxygen stream. This stream issues against a novel baffle that breaks up the bubbles and aids their evaporation and prevents the stream from striking directly against the surface of the water. This keeps the oxygen free of any unabsorbed water or residual droplets. Moreover, the baffle, m combination with a somewhat labyrinthine pathway which the humidified gas must travel in its way to the outlet serves to shake out all of the few such droplets that might remain in the gas. Gas is prevented from building up to high pressures by a safety relief valve that is provided in the cover to the jar. When the pressure reaches a value somewhat above normal but still well within the limits of safe operation, a reed in the relief valve sounds a musical tone to give audible warning that ’ the pressure is excessive.

Further features of the invention will be understood from a detailed description and illustration of one form of the device that embodies the principles of the iny^e“^tl0°> ^{hut tlle} scope of the invention is not intended to be limited thereby except as provided by the appended claims.

In the drawings:

Fig. 1 is a view in elevation showing an oxygen tank, a regulator, gauges, and a humidifier connected thereto.

Fig. 2 is a view in elevation and in section of a humidifier embodying the principles of this invention.

_Λ t ’ ³· 71 ^{a view on a redu}ced scale of a portion of the humidifier adjacent the venturi chamber, looking from the left side in Fig. 2.

Fig. 4 is a view in section of a portion of the safety valve, looking at right angles to Fig. 2 along the line 4—4.

big. 5 is a view in section looking up from the bottom of Fig. 4, along the line 5—5.

Fig. 6 is a view in section of the venturi and baffle oi a modified form of the invention.

Fig. 7 is a view taken along the line 7—7 of Fig. 6 Fig. 1 shows an assembly employing a humidifier embodying the principles of this invention. The dry gas is usually supplied at high pressure from a cylinder 10 filled with oxygen, and its pressure is reduced by a regulator 11. A gauge 12 may indicate the pressure of the gas as it issues from the regulator 11, while a flow measuring device end. A spring

2,709,577 ejected from the nozzle 47 against a stream diverter member or baffle 60. This may comprise a cusp-shaped metallic member 61 supported below the assembly 37 by the metal tube 51 and a solid standard 62. The stream is spread outwardly by the cusp 61, which breaks up its concentration into thm sheet form, prevents the water surface from rippling, and also breaks up any stray water droplets, any remaining free droplets dripping down the member 61 and off it into the water below. The. cusp shape effects a very even distribution of the humidified stream of gas, at the same time causing the stream to turn outwardly'and upwardly without striking the water below. From the baffle 60 the humidified oxygen follows a labyrinthine path to the outlet, going from the jar interior through the holes 36 and the passageway 33 to the OUtlet ¹⁸· ·, Λ _f

A novel pressure-relief valve 79 is also provided, tor the prevention of excessive pressures within the jar 20 and for giving an audible warning when the outlet of gas from the normal outlet is blocked and the pressure builds up. For this purpose a recess 66 is provided in the upper surface of the cover 21, and openings 67 and 68 extend all the way through the cover. The upper portion of the recess 66 is a generally vertical cylindrical wall 71, while 25 the lower portion 72 slopes inwardly to a .flat web 73 that forms the bottom of the recess 66 and is perforated at its center by the opening 67 and bordering it by the openings 68. .

The moving part of the valve 70 comprises a disc 74 30 that fits in the recess 66 and has a rubber O-ring 75 around its periphery, preferably on the lower side so as to seat against the sloping wall 73. When seated, the disc 74 closes the path to gas entering through any of the openings 68. . , A stem 76 depends from the disc 74 down through the central opening 67, a nut 77 being threaded on its lower v..d, A spring 78, held in tension between the nut 77 and the web 73, normally retains the disc 74 in its lower . When the pressure of the gas inside the jar 20 exceeds the tension of the spring 78, the spring 78 is compressed, the disc 74 is lifted, and gas passes between the rubber ring 75 and the walls of the recess 66.

A hollow cap 89 has at its lower end a rubber O-ring 81 that fits in a groove 82 in the recess 66. All the gas 45 escaping past the disc valve 74 goes up through the cap 80. Just below the cap’s upper end is a plate 83, having a small outlet opening 84 and a generally rectangular opening 85. A reed 86 lies across the opening 85, one end being secured to the plate 83 so that its other end can ⁵⁰ vibrate freely in the opening 85. .

An opening 87 through the top of the cap permits escape of the gas after it has passed through the openings 84 and 85. The top of the plate 83, which shows through the opening 87, may be colored red to discourage tamper⁵⁵ ing. However, there is a further safety feature that comes into play if anyone should tape, over the opening 87 or otherwise obstruct it. The O ring 81 connection is air tight, but if the escape opening 87 is blocked, excess pressure will eject the entire cap 80 by lifting it and its ^&lt;i0 O ring 81 out of the recess 82.

In operation, the gas enters at the inlet 17, goes through the tubes 28 and 41 to the vaporizer assembly 37 and issues from the orifice 45 into the chambei 46.. The venturi sucks water in through the ball inlet 53 via the _________; ' There the water is broken up into infinitesimal portions and mixed .with the dry gas to produce gas having up to 10.0% humidity. The humidified gas issues from the nozzle 47 and its „_o stream is then spread by the cusp 61, which breaks up ‘° any droplets and prevents any disturbance of the surface of the water. The gas then goes up into the interior of the jar 20 above the baffle 6®, passes tnrough the holes 36 in the sleeve or muffler tube 35, into the passageway 33, 75 and goes to the outlet 18.

³ may indicate the volume of the gas being humidified, usually expressed in liters per minute. A humidifier 15 that embodies the present invention may be located adjacent the flow measuring device 13. .

The humidifier 15 appears in greater detail in Fig. 2. It includes a housing 16 with an inlet 17 for the dry gas and an outlet IS for the humidified gas.. The housing 16 comprises a jar 20 and a cover 21. The jar 20 will usually be made of glass or other transparent material, so that the water level and the operation of the vaporizer can be watched. Preferably the jar 20 is of the mason-type, having a flat shoulder 22 at the lower end of a threaded neck 23. A rubber gasket 24 rests on the shoulder 22 and effects a seal between the jar 20 and the lower lip 25 of the cover 21. In this manner there is no dependence on the top edge 26 of the jar to effect a seal.

The cover 21 supports the working parts of the humidifier 15. A central tapped hole 27 in its upper surface holds a threaded inlet fitting 28 in the upper end of which is the humidifier inlet 17. A filter screen 29 may fit in the inlet 17 to remove any foreign matter from the incoming gas.

A central bore 30 extends through the cover 21 from the lower end of the hole 27, the bore 30 being flared out at its lower end to provide a socket 31 for a purpose to be explained. An interiorly-threaded annular rim 32 depends from the lower surface of the cover 21, concentric with the socket 31. From a point inside this rim 32 a passageway 33 is bored through the cover 21 to the outlet 18. .

A hollow cylindrical sleeve or muffler tube 35 is threaded into the rim 32. The sleeve 35 has perforations 36 through which the humidified gas passes on its .way to the outlet passageway 33, as shown by the direction of the arrows.

The humidification is done in a vaporizer assembly 37 35 that is threaded into the lower end of the sleeve 35. The assembly 37 comprises a lower member 38 into which an upper member 39 is threaded. The dry gas from the inlet fitting 28 is conducted to the vaporizer 37 by means of a tube 41 held between the socket 31 and a socket 42 . in the upper member 39. An O-ring 43 seals the reduced upper end of the tube 41 at the socket 31 and another O-ring 44 seals the reduced lower end of the tube 41 in the socket 42. This type of fitting makes it easy to disassemble the pieces to sterilize them.

The dry oxygen issues from the upper vaporizer member 39 through a relatively long, narrow, and restricted orifice 45, of a size compatible with the flow measuring device 13. The importance of relating the size of. the orifice 45 to the flow measuring device 13 will be explained

The orifice 45 extends deep into a substantially annular chamber 46 that is formed in the lower vaporizer member 38. The orifice 45 is spaced a short distance from a wider nozzle 47 that leads out from the chamber. 46 through the lower wall of the member 38. This combination of orifice 45, chamber 46, and nozzle 47, forms a venturi whose sucking action is used to draw water up into the chamber 46, where it is broken up into very small particles and is then mixed with the gas.

The water may be drawn in through a flexible tube 50 secured around the projecting lower end of a metal tube 51 which is joined to the chamber 46 by a passageway 52. The proper length of the flexible tube 50 depends on the height of the jar 20, so that it may vary from a few inches to several feet. However, because of its flexibility,, a relatively long piece of tubing 50 may be used inside relatively short jars, so that a single tube 50 may be used for several different sizes of jars 20.

•At the lower end of the tube 50 there may be secured an intake fitting 53, preferably of ball shape so that it may lie in the lowest rim of the jar 20 and suck up water so long as there is water in the jar. To prevent the introduction of foreign particles, the fitting 53 may be provided with a filter 54 adjacent the narrow passageway 55.

The water and oxygen mixed in the chamber 46 are position, where it prevents leakage of gas.

⁰⁵ tubes 50 and 51 into the chamber 46.

2,709,577

An advantage of this device is that the gas will humidify with equal efficiency, no matter what the water level is, and the gas will be humidified so long as there is water in the jar 28. The water level can always be observed through the transparent jar 20 and water added 5 when it is needed.

The safety valve 70 operates only from the gas pressure inside the jar 20. Then, when the gas pressure exceeds the tension of the spring 78, the disc 74 is raised and gas enters the cap 80. It passes through the plate openings 10 84 and 85 out the cap opening 87, sounding the warning reed 85 as it does so. If someone carelessly tapes over the opening 87, the whole cap 80 will be ejected, and the gas will still escape.

It is worth noting that the structure of the humidifier 15 15 makes possible the use of either of two types of flow measuring devices and makes it possible to use them on the dry gas before humidification. One such device is usually termed a “flow gauge.” In reality it is a pressure gauge that is used in conjunction with an orifice of known ²⁰size, the gauge being calibrated to read in terms of the quantity per unit time (e. g. liters per minute) of gas which the pressure would cause to flow through the orifice. A “flow gauge” may be used with the present invention, because the humidifier 15 is of the jet type, and ²⁵its orifice 45 can be standardized, and the gauge calibrated to it.

The second type of flow measuring device that is in common use is usually termed a “flow meter” and is illustrated by the floating ball type of meter. There, gas ³⁰flows from bottom to top through a vertical tube with conical walls that widen gradually toward the upper end. In its flow the gas lifts a light ball to a height that depends on the rate of flow. The ball will drop when there is no flow, even though the pressure of the gas in- ^3acieases. Consequently the “flow meter” is more accurate than the “flow gauge.” For example, if the orifice became stopped up, flow would stop, and pressure would build up; the “flow gauge” would then falsely indicate an increase in flow, whereas the “flow meter” would correctly indicate a cessation of flow.

“Flow, meters” have heretofore been used only at atmospheric pressures, or at least where the outlet end is at atmospheric pressure. With humidifiers this has two principal disadvantages. Wet gas fogs the tube and ⁴⁵makes it difficult to read, and if water has collected on and around the ball, it weighs it down and makes it stick to the walls, so the reading is inaccurate. With this invention, the “flow meter” can be placed on the input side of the humidifier, where the gas is dry, and where ⁵⁰these difficulties are prevented. This is possible, because the orifice 45 is standardized, making it possible to calibrate the tube for operation under the flow valves corresponding to the orifice. Also, the warning reed 86 indicates when the outlet tube from the humidifier is ⁵⁵clogged. When the warning system is silent, gas is flowing out from the humidifier at substantially the same rate it is flowing in.

In Figs. 6 and 7 a modified form of the invention is shown. Here the gas stream entering the vaporizer as- ^Wsembly 140 flows through two orifices 145 of identical size. This enables the use of the same flow meter or flow gauge to indicate a stream of twice as much gas, either by new calibration or by a corrected reading of the old scale. The gas mixes with the water vapor in ⁶⁵ the venturi chamber 146 and flows out through two nozzles 147. The baffle 160 includes a knife-edge cusp member 161 (instead of the point-cusp member 61) so as to take, care of both nozzles 147. Otherwise, operation is identical with the form described in Figs. 1-4.